Plastic Grow-bomb: Hydroponics From Plastic Bags

About: I am a qualified Industrial Designer based in Johannesburg, South Africa, and UK Citizen. I currently am working as a researcher, Industrial Design Lecturer, and direct a registered Industrial Design Company.
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Plastic bags have been given a bad rap in recent years, and this plastic grow-bomb illustrates that there are several benefits to plastic. This is a hydroponic container and experimental growth medium made from predominantly plastic bags. As a further step for redeeming bad karma associated with plastic, I aimed to use the ‘traditional’ origami water bomb for creating a container for sustaining life, rather than what it was used for when I was a child … which was power-slamming water into a peers face.

Instead of recycling, I aimed to use the sheet structure of the plastic bags in the creation of a container which is able to encase a growth medium also made from a shredded plastic bag. Although a piece of rock-wool aids in the initial growth of the plants, it illustrates that this small container proves effective for retaining water/hydroponic growth solution needed by the resident plant.

I tested it with wheat-grass, due to time constraints- but would like to try it with a small seedling.

I would like to experiment with other types of ‘innovative’ growing media, with this hand shredded plastic being a good starting point.

Required Plastic Bags Scissors Waterbomb instructions (a quick google search for Origami Water Bomb will help) Sellotape Rockwool (or suitable seedling material) Water or Hydroponic nutrients. Or a seedling ready to plant could be used (eliminating the need to watch grass grow).

Supplies:

Step 1: The Grow-bomb Casing

Using the standard plastic bag, I flattened it out to allow for cutting out 2 squares: one from each side.

I found the folding instructions for the Origami Water Bomb online, using a quick image search. I followed these step-by-step in creating the casing. The plastic is not as easy to fold as paper, but careful and accurate folding gets the job done.

The final step is to inflate the casing. Once this is done it is evident that the casing can effectively contain water and minimize evaporation/water loss. This provides an indication to its effective application for growing a plant.

Step 2: Finishing the Grow Bomb

Using a few small sections of Sellotape, I reinforced the corners of the casing where it seemed it would separate and come apart. Using a pair of scissors I also trimmed the hole on the top face to be a bit neater.

The form is now ready for filling with the growing medium which would give something for the roots to grip to.

Step 3: Shredded Plastic Growing Medium

I took another plastic bag, and cut it into manageable sections. I then folded/rolled them into stack which would allow me to cut through many layers at once.

I cut as small sections as I could which had to then be separated/teased by hand to fluff them out.

Once complete, I took small bunches of these plastic ribbons and stretched them out: creating small thin filaments alongside thin flat narrow strips. All the shredded plastic used in this instructable was created from one plastic bag.

This ‘filling’ must then be stuffed into the pre-constructed grow bomb casing.

Step 4: Stuffing the Turkey

The tricky part is getting the entire casing filled with the shredded plastic.

I used several methods, including small pinches of filling stuffed in with the back of a pencil, and rolling a small paper funnel used in conjunction with the pencil.

Because the plastic is so soft and flexible, getting it all into the casing didn't turn out to be too much of a hassle.

Step 5: Rock Wool and Seeds

I took one segment of rock wool, and managed to get it fitting inside the opening of the grow bomb.

The rockwool is a fibrous block which creates a nice environment for seeds to begin to grow. This website has a good overview, if you have never been introduced to rockwool. Once the roots grow out through the bottom of the rock wool, they will then begin growing through the shredded plastic.

I trimmed the opening slightly to expose the entire top surface of the rockwool as I will be planting a bunch of wheatgrass seeds. I am using wheatgrass as it grows fast, and will allow for me to test this container. I know that there are many ways to grow wheatgrass, but I was not willing to wait 3 months for some basil seeds to get to the same height as one weeks wheatgrass growth.

Step 6: Water and Wait

Water using a suitable fluid. I used a weak hydroponic growing solution which I use on several of my plants.

From the images you can see how the rock-wool remains wet, and the seeds begin to sprout.

The plastic casing retains water very well, and retains moisture as evaporation is only possible through the opening.

I am interested in seeing other experimental hydroponic growing containers and especially the growing mediums, and testing other ideas which I think of.

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6 Discussions

Is shredded plastic a useful medium? I suspect water would pool and stagnate in the cavernous upcycled shelter. With no wicking medium, anything the roots don't use will likely contribute to anaerobic pathogens. The roots will also struggle to expand beyond the rockwool for the same reason. Perhaps ironing the folded bag before shedding would yield a thickness that could better support the roots, while avoiding trapped air obstacles (fewer shredded pieces).